I fetched a kernel from kernel.org (5.6.14 and 5.7.0-rc7). 

make menuconfig

Device Drivers -> Input device support -> Touchscreens -> Elan eKTH I2C touchscreen  -->> set to m

rebuild kernel and install...

The driver is no longer loaded as built in, but as a module. This leads to a delay of ca. 3-4s. Somehow this seems to help.

The Touchpad/screen is connected via i2c1.

dl3it@IdeaPad:~$ dmesg | grep ELAN
[    1.583560] i2c_hid i2c-ELAN0001:00: supply vdd not found, using dummy regulator
[    1.583575] i2c_hid i2c-ELAN0001:00: supply vddl not found, using dummy regulator
[    1.646025] input: ELAN0001:00 04F3:3140 Mouse as /devices/platform/AMDI0010:01/i2c-1/i2c-ELAN0001:00/0018:04F3:3140.0001/input/input5
[    1.646257] input: ELAN0001:00 04F3:3140 Touchpad as /devices/platform/AMDI0010:01/i2c-1/i2c-ELAN0001:00/0018:04F3:3140.0001/input/input6
[    1.646347] hid-generic 0018:04F3:3140.0001: input,hidraw0: I2C HID v1.00 Mouse [ELAN0001:00 04F3:3140] on i2c-ELAN0001:00
[    4.456207] input: ELAN0001:00 04F3:3140 Mouse as /devices/platform/AMDI0010:01/i2c-1/i2c-ELAN0001:00/0018:04F3:3140.0001/input/input8
[    4.456459] input: ELAN0001:00 04F3:3140 Touchpad as /devices/platform/AMDI0010:01/i2c-1/i2c-ELAN0001:00/0018:04F3:3140.0001/input/input9
[    4.456574] hid-multitouch 0018:04F3:3140.0001: input,hidraw0: I2C HID v1.00 Mouse [ELAN0001:00 04F3:3140] on i2c-ELAN0001:00



dl3it@IdeaPad:~$ xinput
⎡ Virtual core pointer                    	id=2	[master pointer  (3)]
⎜   ↳ Virtual core XTEST pointer              	id=4	[slave  pointer  (2)]
⎜   ↳ ELAN0001:00 04F3:3140 Mouse             	id=11	[slave  pointer  (2)]
⎜   ↳ ELAN0001:00 04F3:3140 Touchpad          	id=12	[slave  pointer  (2)]
⎣ Virtual core keyboard                   	id=3	[master keyboard (2)]
    ↳ Virtual core XTEST keyboard             	id=5	[slave  keyboard (3)]
    ↳ Power Button                            	id=6	[slave  keyboard (3)]
    ↳ Video Bus                               	id=7	[slave  keyboard (3)]
    ↳ Power Button                            	id=8	[slave  keyboard (3)]
    ↳ Integrated Camera: Integrated C         	id=9	[slave  keyboard (3)]
    ↳ Ideapad extra buttons                   	id=10	[slave  keyboard (3)]
    ↳ AT Translated Set 2 keyboard            	id=13	[slave  keyboard (3)]

libinput:

Device:           ELAN0001:00 04F3:3140 Mouse
Kernel:           /dev/input/event5
Group:            8
Seat:             seat0, default
Capabilities:     pointer
Tap-to-click:     n/a
Tap-and-drag:     n/a
Tap drag lock:    n/a
Left-handed:      disabled
Nat.scrolling:    disabled
Middle emulation: n/a
Calibration:      n/a
Scroll methods:   *button
Click methods:    none
Disable-w-typing: n/a
Accel profiles:   flat *adaptive
Rotation:         n/a

Device:           ELAN0001:00 04F3:3140 Touchpad
Kernel:           /dev/input/event6
Group:            8
Seat:             seat0, default
Size:             100x66mm
Capabilities:     pointer gesture
Tap-to-click:     disabled
Tap-and-drag:     enabled
Tap drag lock:    disabled
Left-handed:      disabled
Nat.scrolling:    disabled
Middle emulation: disabled
Calibration:      n/a
Scroll methods:   *two-finger edge
Click methods:    *button-areas clickfinger
Disable-w-typing: enabled
Accel profiles:   none
Rotation:         n/a


I'll add a dmesg and Xorg log...